At present, double enzyme method is employed to produce corn starch syrup. This method involves the following processes: corn—cleaning (impurity removal)—steeping—separating germ by wet milled method—separating fiber—separating gluten (separating proteins)—starch milk—gelatinization and liquefaction (adding high temperature-resistent α-amylase)—saccharification (adding glucoamylase)—corn syrup (Liu Yawei, Technology of Corn Starch-Producing and Converting [M], Chemical Industry Press, Beijing, 2004; You Xin, Manual of Production and Application of Starch Sugars [M], China Light Industry Press, Beijing, 1999; M. J. E. C. van der Maarel, etc. Properties and Applications of Starch-converting Enzymes of the α-amylase Family. Journal of Biotechnology, 2002, 94:137-155). The above method will consume a significant amount of water and electricity and pose environmental pollution problems.
Scholars in China have tried to use extrusion-expanding corn degermed to produce corn starch sugars (Yang Mingduo, Study on the Application of Extrusion-Expanding Technology in the Production of Starch Sugars, Journal of the Chinese Cereals and Oils Association [J], 1989 (2): 38˜45; Yang Erna, The Technology of Starch Sugar[M], Heilongjiang Science and Technology Press, Harbin, 1990:231˜232). The technology involves the following processes: corn—cleaning (impurity removal)—extrusion-expanding of the degermed corn flour—slurrying (the ratio of extrusion-expanding degermed corn flour to water is 1:5 or 1:6)—liquefaction (adding medium-temperature amylase, raising the temperature to 88-92° C.)—saccharification (adding glucoamylase)—corn syrup. To date, it is still hard for this technology to be applied to actual production due to the difficulties in the saccharification and filtration of the saccharification liquor.
Chinese patent CN200510045327.1 to Shen Dechao (Title: Processing method and device for the extrusion-cooking of raw materials for starch syrup, and saccharogenic method of the extrusion-cooked raw materials for starch syrup; Application date: Dec. 9, 2005) addresses the above-said difficulties in the saccharification and filtration of the saccharification liquor. However, a saccharification time of about 30 hours is still needed in order to obtain corn syrup with relatively higher DE value, for example DE=95%.
Chinese patent CN200710015601.X to Shen Dechao (Title: Processing method and device for the extrusion of raw materials with enzymes added for starch syrup, and saccharogenic method of the extruded raw materials for starch syrup; Application date: May 11, 2007) favorably solves the above problem, so that a saccharification time of less than 30 hours is needed in order to obtain corn syrup with relatively higher DE value, for example DE=95%.
However, the above-mentioned prior art did not disclose the kind and amount of enzymes added prior to extrusion of raw materials for starch syrup, the kind and amount of α-amylase added in the gelatinization stage of the saccharification process, and the kind and amount of glucoamylase added in the saccharification stage of the saccharification process. The parameters of the prior-art processing method and device for the extrusion of raw materials for starch syrup with enzymes added are still less than appropriate, and the saccharogenic method of the extruded raw materials for starch syrup needs further improvement.
Extensive experiments indicated that only by overcoming the above disadvantages of prior art, can the starch in the raw materials for starch syrup extruded with enzymes added be degraded more thoroughly, and therefore saccharified more efficiently.